Is this a bad power supply?

[RoyaL-TigeR]

I recently just finished putting a computer together and when I turned it on it does this really weird thing. It would power up for a bout a few seconds, shuts everything down, and power up again and everything runs fine. I checked the plugs and they all seems to be plugged in tightly. So do you guys think it's the power supply that is doing this?

Thanks in advance

 

[PC eye]

Sounds more like a bios problem since the system runs normally following the immediate shutdown. A faulty supply with a bad cap or transformer would fail on the second attempt.

Did you enable any power on features like power on by usb keyboard or mouse or power on after ac power failure? Sometimes those get a little touchy where the system will simply come on by itself for no reason after being turned off.